Bielefeld, Univ., Diss., 2001. / Computerdatei im Fernzugriff.

Bielefeld, Univ., Diss., 2001. / Computerdatei im Fernzugriff.

Göttingen, Universiẗat, Diss., 2002.

Bielefeld, Universiẗat, Diss., 2001.

No description available.

Page i was not in the other copies of this thesis. -Digitization Centre / Tn5 mutagenesis was used to generate four independent mutants of Rhizobium meliloti that were unable to grow on protocatechuate (Pca-). Two of the Pca- mutations were mapped to a region of the second symbiotic megaplasmid (pRmeSU47b) previously shown to be required for growth on protocatechuate. This pca locus was shown to consist of the first five structural genes of the protocatechuate branch of the B-ketoadipate pathway, in the order pcaDCHGB. This gene order is the same as determined for Agrobacterium tumefaciens. An additional reading frame with homology to LysR-type regulators was found to be upstream of, and transcribed divergently to the pcaDCGHB operon. This is likely to fulfil the same role as the regulatory gene, pcaQ, of A. tumefaciens. A cosmid plasmid which carried these pea genes failed to complement the Pca- phenotype of a strain carrying a 300 kb megaplasmid deletion encompassing this pea locus. This implies that another pca locus, perhaps pcaIJ, is present within the deleted region of the rnegaplasmid. Two Pca- Tn5 insertions which did not map to the megaplasmid locus were isolated. One of these insertions appears to be in a catalase gene. / Thesis / Master of Science (MS)

Genetic mapping of pDS15 revealed that this cosmid clone carries the Sinorhizobium meliloti TCA cycle genes mdh, sucCDAB, sdhAB and part of lpdA. Three genes (mdh, sucC , and sucA) were completely sequenced and submitted to GenBank. The nucleotide and amino acid sequences of the TCA cycle genes encoded on pDS15 were aligned and found to be highly homologous with other closely related rhizobial species. S. meliloti cells grown in LBmc express the mdh-sucCDAB operon as one transcript, based on RT-PCR results. Alternative sigma factor sigma54 was not found to have a role in mdh-sucCDAB expression. Despite considerable effort, we have not been able to isolate sucA mutants via random transposon Tn5tac1 mutagenesis to date. Homologous recombination between a plasmid-borne sucA::Tn5 and wild-type S. meliloti sucA failed to generate a bona fide mutant, as revealed by Southern blot analysis. Plasmid pDS15 was mutagenized with transposons Tn5, Tn5tac1, and Tn5-B20. Three Tn5-B20 insertions were mapped to mdh, sucD, and sucA respectively, and preliminary gene expression studies were done.

No description available.

Thesis (Ph.D.) -- McMaster University, 1997. / Includes bibliographical references (leaves 237-260). Also available via World Wide Web.

Techn. Universiẗat, Diss., 2000--Berlin.